What type of gases holds in heat and keeps the earth at a moderate temperature?
primary gases
ozone layer
trace gases
greenhouse gases

Which of the following statements about the migration of workers to other countries is false?

Residents of moldova are mainly a. russian b. ukrainian c. serbian d. romanian the answer is d. romanian

Which ecosystem best fits the characteristics listed below? which ecosystem best fits the characteristics listed below? ii. seasonal migrations of millions of wildebeests, zebras, and elephants iii. large numbers of predators, such as lions iv. acacia trees and grasses a. the congo rainforest b. the african mangroves c. the serengeti grasslands d. the sahel